Process of manufacture of artificial silk and of artificial threads or filaments



May 4 1926. 1,583,475

J. E. G- LAHOUSSE PROCESS OF MANUFACTURE OF ARTIFICIAL SILK AND OFARTIFICIAL THREADS OR FILAMENTS Filed Sept. '26, 1924 CD E: k

l N V E N TO R: (Ree 6 [a ouq Gus'fre Label/s 0 ATTORNEY Patented May 4,1926..

UNITED STATES PATENT OFFICE.

JOSEPH EDOUARD GUSTAVE IIAHOUSSE, OF TERNAY FRANCE, ASSIGNOR TC SOCIETEPOUR LA FABRICATION DE LA SOIE RHODIASETA, OF. FARIS, FRANCE,

, PROCESS OF MANUFACTURE OF ARTIFICIAL SILK AND OF ARTIFICIAL THREADS.CR

rILAMEN'rs- Application filed Septemberfi, 1924. SerielIIo. 739,972.

To all whom it may-camera."

' Be it known that I, JosErH EDOUARD GUs'rAvr. LAHOUSSE, residing atTernay, France, a citizen of the Republic of France,

5 have invented'certain new and useful Improvements in Processes ofManufacture of Artificial Silk and of Artificial Threads or Filaments,of which the following is a spec ifi'cation.

ally, of any artificial threads, filaments or fibres by the processcalled dry spinning. It is particularly, applicable to the spinning ofasolution of cellulose acetate and, generally, of any ester, ether orcellulose deriyative or of a mixture of these products with or withoutaddition of other compounds in a solvent or solvent mixture whichevaporates while producing the manufactured artificial filaments.

Usually, the atmosphere introduced into, the cell, b or near the outletof the filaments or e sewhere, in order to "evaporate the solvents ofthe travelling filaments, is pure or has been freed from'solvents ascompletely as possible, so that the vapors of solvents taken away fromthe filaments con tribute alone, or practicallalone, to the loading ofthe medium wit vapor of solvents. Y When the evaporation of the solventor solvents takes place in an atmosphere which a does not'contain any,or only a little of thevapour of the solvent a skin which is al- (Timthe surface of themost dry is produce filament as soon as it issues fromthe die. This film, which is much less plasticthan the core of thefilament, must subsequently flatten orv crack to adapt itself tothediminution of volume sufiered by the filament owing to the drying ofits core, and also to the stretching to which it is generally subjected,this being detrimental to the appear.

the evaporation of the solvent or solvents,

The present invention is relative to the manufacture of artificial silk,and, gener-- ance of the thread and to its mechanical properties.Moreover, the presence of this;

not as hitherto in'a medium containing only a small proportion ofvapours of the solvent or solvents, but, on the'c'ontrary, in a mediumpreviously richly laden but not superficial evaporation and the speed ofdiffusion of the solvent of the core towards the surface. It is possibleto cause it to vary by varying the degree of saturation of the medium inwhich evaporation takes place, the temperature of this medium and thatof the material issuing from the dies. The lat ter is brought to therequired temperature 9 and the most economical concentration consistentwith the. permissible pressure inthc apparatus is chosen.

By varying the above indicated factors, one can vary considerably thesha e of the cross-section of the filaments and o tain sections of anyshape, from sections extremely twisted, recalling the appearance ofletters of the alphabet, to almost circular. shapes.

According to the shape of its cross-section,.the silk is more or lessbright, and is more or less smooth to the touch. A new manner of varyingthese properties and of satisfying the exigencies offashion, withoutchanging the manufacturing device is thereby obtained.

Independ ntly of the above advantages.

arising out of the control of form ofthe",

cross-section of the artificial filament, the

process which is the object of the-present in;

vention permits besides, owing to the greater permeability of thesurface of the filament, the obtainme'nt of a more rapid drying andconsequentlytheincreasing or the production of the spinning plant.Moreover, it permits the operation of the recovery ofthe solvent orsolvents b direct condensation.

The atmosphere w 'ch penetrates into the cell of the spinningap'paratusis, according to this invention, a gaseous medium. saturated withvapours of the solventejat a suitable temperature t, lower than thatinside the cell. In. the cell it becomes richer owing to the vapoursfrom the filaments which are drying, and becomes capable of depositingby direct condensation, at the temperature 25, the solvent taken fromthe filaments in this manner. For this, it is caused to pass through thecoil of a condenser or any other heat exchanging apparatus cooled to thetemperature I It issues saturated at that temperature and thence, tobegin the cycle over again, it is sent back to the spinning cell,becoming again apt to cause the evaporation of the solvents of thefilaments simply by being reheated either before or after entering thecell.

The circuits followed by the evaporating medium must of course be asfree from leakage as possible, that is, it must constitute a'closedsystem exchanges with the external atmosphere being only possible by thesmall orifice provided as an outlet for the fila-J ments. Theseexchanges can be reduced to a very small amount, if the orifice issmall, and any leakage of solvent through this orifice can be avoided inany case by creating there a very slight aspiration which causes astream of air, which may be extremely small, directed from the exteriorto the interior and opposing any leakage of the evaporating medium. Acorresponding quantity of gas will of course be abstracted from thatbelonging to the cycle at another point of the circuit, and, howevernegligible its amount, it can be subjected to any suitable treatment forthe purpose of recovering the solvents it contains. H

As the density of the evaporating medium varies according to itstemperature and according to the more or less great quantity of thesolvent it carries, the various elements of the circuit (spinning cell,condenser of the solvents to be recovered, reheating system for thegases) may be arranged so that its circulation in this circuitautomatically takes place by the sole effect of the difierences ofdensities. This circulation may also be caused-by any suitablepropelling apparatus, ventilator, fan, pump or the like, this permittingthe arrangement that the evaporating medium enters the spinning cellandissues from it at .any points as may be considered advantageous. Asingle ventilator may} be used for one or more series of cells, thelatter case being particularly advantageous as it permits theperformance of a single condensation and a single reheating of the gasesfor one or several series of cells. This ventilator can,

- of course, act directly by suction and by forcing under pressure inthe cells, or by the draught induced in the individual circuit of eachcell. In orderto equalize the gaseous flow in each cell, the arrangementdescribed in the co-pending application of Grillet, Serial No. 697,029,filed March 5, 1924, will be adopted for all the piping systems.

The circulating medium may be the air of the shed, laden with thevapours of the solvents, but, in view of the danger of explosion due tothe vapours of inflammable solvents carried by the medium, a gas, orgaseous mixture, not containing oxygen may be caused to circulate in thesystem and to act as carrier for the vapours of the solvents. Evidently,a little air Will always enter in the cells by the orifice of issue ofthe filaments, but the proportion of oxygen in the circulatinggases canalways be kept constant and very small by introducing regularly into thecycle a certain quantity of'an inert gas at another point of thecircuit.

Referring to the appended drawing, which illustrates diagrammatically,as an example, an apparatus constructed according to the principlesdescribed above a is the spinning cage and b is the spinning die. Thesolution to be spun enters by a jacketed pipe 0 allowing it to be heatedby steam'or hot water or air. The filament issues from the cell by theorifice (Z to proceed to any other desired apparatus for furthertreatment or bobbining. The gases aspirated by the air fan or pump eleave the.

cell at f and pass into the condenser g,-'

Where they are cooled to the temperature f and freed from the solventsgiven out from the filaments, which solvents are collected by means ofthe tube h which dips into the vessel 5 filled with solvent andconstituting a liquid seal preventing .all communication between theevaporating medium and the external atmosphere. From the condenser thegases pass through the air pump e, through the heater j, andre-enter'the cell at k. If desired, the cell may be heated.

by means of the heating coil m, situated at the bottom of the cell. Asmall quantity of gas, corresponding to the quantity of air which hasentered the cell by the orifice d, is abstracted by the tube '12., andis led to a suitable apparatus not shown, for the recovery of thesolvents.

What I claim and desire to secure by Letters Patent is e 1. A method ofcontrolling the section of artificial silk and other threads, filamentsand fibres obtained by dry spinning in aclosed cell of a solution of acellulose derivative in a volatile solvent, which consists inintroducing into the cell a gaseous evaporating medium previously richlyladen with a-determined proportion of vapors of the solvent, but notsaturated, at the temperature prevailing in the cell.

2. A method of controlling the section of artificial silk and otherthreads, filaments and fibres Obtained by dry spinning in a closed cellof a solution of a cellulose derivative in a volatile solvent, whichconsists in causing a'gaseous evaporating medium to circulate through apiping circuit coupling a spinning cell, in a cycle in the course ofwhich it enters into the cell richly laden with vapors of the solvents,but not saturated, at the temperature prevailing in the cell and loadsitself further with the vapors of the solvent taken away from thefilaments, issues from the cell and is partly freed from the vapors ofthe solvent by cooling. and direct condensation, said evaporating mediumbeing then reheated and returned to the cell to go through the cycleagain, being richly laden with vapors of the solvent in a proportionwhich is determined by the temperature at which said condensation takesplace.

3. An a paratus of the character described, W ich comprises a closedcell, a spinning die within said closed cell through which a solution ofa cellulose derivative is led under the pressure by suitable means, anoutlet for the spun filaments, an inlet and an outlet for theevaporating medium, a piping circuit connecting said inlet and outletoutside the cell, means connected to the said circuit for condensing thevapors of the solvent in the evaporating medium, means for heating theevaporating medium, means for causing a circulation of the saidevaporating medium in the circuit, and means for abstracting a smallquantity of the evaporating medium from the circuit thereby causing aslight aspiration in the cell to prevent leakage of the solvent by theoutlet for the spun filaments.

4:. Artificial silk and other threads, filaments and fibres of variedcross section, ob tained by a method of dry spinning of a solution ofcellulose derivative in a suitable solvent by introducing intothe cell agaseous evaporating medium richly laden with a determined quantity ofthe vapors of the solvent, but not saturated, at the temperatureprevailing in the cell.

In testimony whereof I have signed my name to this specification.

JOSEPH EDOUARD CUSTAVE LAHOUSSE.

